Technical Memorandum Work Order #4-F. Prepared for. Metropolitan Transit Authority of Harris County

Transcription

1 DEMAND MANAGEMENT FOR AM AND PM OPERATONS 1-10 KA1Y FREEWAY TRANS'WAY Technical Memorandum Work Order #4-F Prepared for Metropolitan Transit Authority of Harris County Texas Transportation nstitute The Texas A&M University System College Station, Texas June 1990

2 TABLE OF CONTENTS NTRODUCTON REPORT ORGANZATON AM PEROD OPERATNG CONDTONS Vehicle Demands Travel Time and Speed Capacity Analysis Summary of AM Peak Period Operations OPTONS FOR MANAGNG DEMAND DURNG THE AM PEAK PEROD Voluntary Spreading of Peak Hour Demand mposing a 3 + Carpool Definition during the Peak Hour Require Authorization during the Peak Hour Close and/ or Meter Entrance Ramps during the AM Peak Hour Recommendations PM PEROD OPERATNG CONDTONS Vehicle Demands Travel Time and Speed Capacity Analysis Summary of PM Peak Period Operations OPTONS FOR MANAGNG DEMAND DURNG THE PM PEAK PEROD Voluntary Spreading of Peak-Hour Demands mposing a 3 + Carpool Definition during the Peak Hour Require Authorization during the Peak Hour Close and/ or Meter Entrance Ramps during the PM Peak Hour Recommendations REFERENCES Page

3 LST OF FGURES 1. Katy Freeway Transitway, AM Peak Hour Transitway Page Vehicle Utilization 2 2. Katy Freeway Transitway, PM Peak Hour Transitway Vehicle Utilization 3 3. Katy Transitway Eastbound, AM Peak Hour Volumes, April Katy Transitway Flow Rates, Eastbound, AM Peak Period Katy Freeway/Transitway Average Speeds, Eastbound, AM Peak Period Katy Transitway Westbound, PM Peak Hour Volumes, April Katy Transitway Flow Rates, Westbound, PM Peak Period Katy Transitway Flow Rates, Westbound at Silber, Weekday and Fridays Katy Freeway/Transitway Average Speeds, Westbound, PM Peak Period 41 V

4 LST OF TABLES Page 1. AM Peak Period Vehicle Volumes, 1-10 Katy Transitway 7 2. AM Peak Hour Vehicle Volumes, 1-10 Katy Transitway 8 3. Katy Transitway Eastbound 5-Minute Flow Rates, May Results of Travel Time Studies, AM Peak Period, March AM Peak Period Sample Speed Study Results Basic Section Level-of-Service, AM Peak Hour Summary of AM Peak Period Operations, Katy Transitway Post Oak Terminus AM Travel Volumes Before and After Change in Occupancy Requirements, Katy Freeway Corridor Estimated Factors for Converting Unauthorized Carpool Demand to Authorized Carpool Demand PM Peak Period Vehicle Volumes, 1-10 Katy Transitway PM Peak Hour Vehicle Volumes, 1-10 Katy Transitway Katy Transitway Westbound 5-Minute Flow Rates, May Comparison of Weekday and Friday Afternoon 5-Minute Flow Rates, Katy Transitway at Silber PM Peak Hour and Peak Period Demands Observed at Silber Results of Travel Time Studies, PM Peak Period, March PM Peak Period Sample Speed Study Results Basic Section Level-of-Service, PM Peak Hour Summary of PM Peak Period Operations, Katy Transitway Post Oak Terminus 44 v

5 NTRODUCTON Phase 1 of the Katy Transitway opened in October At that time, only authorized buses and vans were allowed to use the transitway; fewer than 100 vehicles used the transitway during the peak hour. n order to address a public perception that the transitway was underutilized, the following actions have been taken to manage vehicular volumes on the transitway: o o o o o April authorized carpools were allowed to use the transitway; July authorized 4 + carpools were allowed to use the transitway with only 3 + occupants in the vehicle; September authorized 3 + carpools were allowed to use the transitway; August carpools were allowed to use the transitway and authorization requirements were eliminated; and October between 6:45-8:15am, carpools must meet a 3+ occupancy requirement to use the lane. Removing authorization and allowing 2+ carpools to use the transitway significantly increased transitway usage beginning in 1986 (Figure 1). n addition, the completion of Phase 2 of the transitway in July 1987 generated approximately a 15 percent increase in the AM peak hour carpool volume; data collected in early September indicated that, with the reopening of school, the peak-hour demand on the transitway increased by an additional 5 percent to 10 percent. Approximately 1,350 to 1, carpools used the transitway during the AM peak hour prior to implementation of the 3 + restriction. Demands during the peak have effectively been controlled during the AM peak hour with approximately 1,090 vehicles observed in December The 1.5 mile Eastern Extension opened in January 1990 and traffic demands during the peak hour have increased by only 150 vehicles (14%) in the AM peak hour. Vehicle demands during the PM operating period were not impacted by the 3 + restriction imposed during the AM peak period (Figure 2). The opening of the Eastern Extension has resulted in an approximate 15 percent increase in vehicle demands on the 1

6 Figure 1. Katy Freeway Transitway, AM Peak Hour Transitway Vehicle Utilization KATY FREEWAY (H 1 OW) TRANSTWAY A.M. PEAK HOUR TRANSTWAY VEHCLE UTLZATON 1,750 1 rr"a"nsfrway t:rra"ns~ay io GESSNER ito WESi BELi ----> ----> iranstway EASiERN 10 SH 6 EXTENSON OPENS (/) w...j u w > u... 0 N 0:: w CD 2 :::::> z '""""WAY CAl''"" lf<-:1 _,.;<.,T t~\~ ""'0"""' 11' '"""'~~"1 ; 1.soo l 1 Ji \ ~f 1,250 1, lh y<,,( ~~-. f, l ~ ~' t, ;r -~ {f \0\~4 0 T OCT84 OCT85 OCT86 OCT87 OCT88 OCT89 OCT90 KATY TRANSTWAY PHASE 1, POST OAK TO GESSNER (4.7 M.), OPENED OCTOBER 29, 1984 TRANSTWAY EXTENSON FROM GESSNER TO WEST BELT (1.7 M.) OPENED MAY 2, 1985 OFF-PEAK, UNAUTHORZED&: 2+ CARPOOL OPERATON BEGAN AUGUST 11, 1986 TRANSTWAY EXTENSON FROM WEST BELT TO SH 6 (5.0 M.) OPENED JUNE 29, CARPOOL REQUREMENT FROM 6:45 TO 8:15A.M. MPLEMENTED OCTOBER 17, 1988 TRANSTWAY EASTERN EXTENSON (1.17 M.) OPENED JANUARY 9, 1990 DATA COLLECTED BETWEEN GESSNER AND POST OAK SOURCE : TEXAS TRANSPORTATON NSTTUTE LEGEND: T =TOTAL HOV VEHCLES B = TOTAL BUSES V =TOTAL VANPOOLS C =TOTAL CARPOOLS

7 w (/) w _j u :r: - w > w :::: w m 2 :::::> z Figure 2. Katy Freeway Transitway, PM Peak Hour Transitway Vehicle Utilization 1,800 l 1 TRiiiSiiwAY f,;;;-;,r;w., TO GESSNER TO WEST BELT ~ 1,600 1,400 1,200 1, r ~ NOTE : PEAK HOUR DEfiNED AS HOUR DURNG WHCH PERSON MOVEMENT S GREATEST KATY FREEWAY (H 1 OW) TRANSTWAY P.M. PEAK HOUR TRANSTWAY VEHCLE UTLZATON il ---> ----> TRANSTWAY TO SH 6 l-~ :r!j~~ 1-~~T--i ~. r J. ;;<. l?~,.~ ~ :. 14. ~ ~ '/ ref e' -.. A 1' ~~,_./; 'e-' \, y,fo., 1' 'f' ~ "! j'ri i~y~'/ v v " k EASTERN EXTEiNSON OPENS ~ ' \ t 0 T" OCT84 OCT85 OCT86 OCT87 OCT88 OCT89 OCT90. KATY TRANSTWAY PHASE 1, POST OAK TO GESSNER (4.7 M.), OPENED OCTOBER 29, 1984 TRANSTWAY EXTENSON FROM GESSNER TO WEST BELT {1.7 M.) OPENED MAY 2, 1985 OFF-PEAK, UNAUTHORZED & 2+ CARPOOL OPERATON BEGAN AUGUST 11, 1986 TRANSTWAY EXTENSON FROM WEST BELT TO SH 6 (5.0 M.) OPENED JUNE 29,1987 TRANSTWAY EASTERN EXTENSON (1.17 M.) OPENED JANUARY 9, 1990 DATA COLLECTED BETWEEN GESSNER AND POST OAK SOURCE : TEXAS TRANSPORTATON NSTTUTE LEGEND: T =TOTAL HOV VEHCLES B =TOTAL BUSES V =TOTAL VANPOOLS C =TOTAL CARPOOLS

8 transitway (1,290 vph in December 1989; 1,500 vph in April 1990) in the PM peak hour. Queueing within the Post Oak/Eastern Extension merge has been observed to occur for periods of time during the PM peak hour, particularly on Fridays. The objective of the transitway is to provide a reliable, high-speed travel alternative; the travel time savings and reliability offered by the transitway provide the incentive for travelers to use high-occupancy vehicles. t is imperative that traffic volumes using the transitway be managed at a level that avoid the creation of significant congestion on the transitway. n managing vehicle volumes on a transitway, the intent is to strike a balance between two competing needs. First, a sufficiently high volume, probably at least 600 vph, must be maintained during the peak hour so that the facility appears to be adequately used to those individuals travelling in the congested freeway general-purpose lanes. Second, the flow rate using the lane during the peak hour needs to be kept below about 1,400 vph so that the lane operates at a high speed and offers a reliable travel time. t should be noted that both METRO and SDHPT have agreed that high-speed and reliable trip times should be provided on the Houston transitway system. Managing the demand on the transitway is further complicated by at least one other factor. Transitway facilities have exceedingly high peaking characteristics; this means that the vehicle volume on either side of the peak hour is only about half of the peak-hour volume. Thus, the need exists to manage the peak-hour volume without adversely affecting the volumes on either side of that peak hour. Experience in Houston has demonstrated that the design of the transitways (i.e., physical separation from the freeway lanes with limited access/egress opportunities) combined with the routine enforcement that is provided make a variety of innovative demand management strategies feasible. There are two specific concerns to be addressed within this report: 1) continuance of the 3+ carpool requirement from 6:45am to 8:15am; and 2) what action, if any, should be implemented to manage demand during the PM peak period. 4

9 REPORT ORGANZATON This report is organized into two major sections. The first addresses operations during the AM peak period, while the second section examines PM operations. This will allow for an independent analysis of the two operating periods since each has unique operating characteristics. Data collected by Til from January to May 1990 are used to define the current operating conditions of the Katy Transitway. Til has prepared numerous reports documenting operations of the transitway. The more recent reports are listed in the reference section of this report. 5

10 AM PEROD OPERATNG CONDTONS The transitway presently operates in the eastbound direction from 4:00 am to 1:00 pm during normal work days. The HOV lane is used by buses, vanpools, and 2+ person carpools; a 3 + occupancy restriction is presently (May 1990) implemented between 6:45-8:15am. The opening of the 1.5 mile Eastern Extension occurred on January 9, The Northwest Transit Center became operational on April 1, Concerns have been expressed by the public that the 3 + restriction is no longer necessary since a majority of HOV users exit the facility using the Eastern Extension instead of the signalized intersection at Post Oak. Vehicle Demands TTl collects vehicle and passenger data at three locations along the Katy Transitway: East of Addicks, at the Post Oak Terminus, and the Eastern Extension. Although the data is collected only one day each month, the values reported are representative of typical operations for normal non-incident conditions on the HOV lane. Table 1 presents transitway demands as observed during the AM peak period (6:00-9:30 am) since the Eastern Extension opened. Total vehicle demands at Silber have been steadily increasing since the beginning of the year. Peak period demands for those entering west of Gessner have remained almost constant. Demand for the Gessner slip ramp entrance has increased from 915 to 1,667 vehicles during the peak period; an increase of 82 percent. Since the Post Oak exit demands have remained constant, the increase at the Gessner entrance is due to an additional approximate 700 vehicles per peak period using the Eastern Extension in April as compared to January The effect of the Northwest Transit Center on transitway operations has been minimal. Buses accounted for only 4 percent of the total vehicle demand during the April 1990 AM peak period; buses and vanpools comprise the remaining 96 percent. Table 2 presents similar data for the AM peak hour. The determination of the peak hour was based upon the maximum vehicle demand at Silber. This was estimated by summing 15-minute data from the Post Oak and Eastern Extension count locations; the maximum hourly flow is reported. This should not be confused with other TTl reports 6

11 Table 1. AM Peak Period Vehicle Volumes, 1-10 Katy Transitway Entering West Entering Demand Exiting at Exiting to Time Period of Gessner at Gessner at Silber Post Oak 1-10 EB January 1990 Buses Vanpools Carpools Total February 1990 Buses Vanpools Carpools Total March 1990 Buses Vanpools Carpools Total April1990 Buses Vanpools Carpools Total NOTES: AM Peak Period is 6:00-9:30 am. Demand at Silber represents maximum demand between Gessner and Post Oak. 7

12 Table 2. AM Peak Hour Vehicle Volumes, 1-10 Katy Transitway Entering West Entering Demand Exiting at Exiting to Time Period of Gessner at Gessner at Silber Post Oak 1-10 EB January 1990 (6:15-7:15) (6:30-7:30) Buses Vanpools Carpools Total February 1990 (6:15-7:15) (6:30-7:30) Buses Vanpools Carpools Total March 1990 (6:15-7:15) (6:30-7:30) Buses Vanpools Carpools Total April1990 (6:00-7:00) (6:30-7:30) Buses Vanpools Carpools Total NOTES: Demand at Silber represents maximum transitway demand. Demand entering at Gessner calculated from values on table; travel time differences not considered. (6:15-7:15) denotes peak hour. 8

13 which present peak hour totals that are typically based upon maximum hourly passenger volumes. A separate peak hour was determined for the west of Gessner location; the peaking characteristics of the two locations (west of Gessner and at Silber) differ because of travel time. The highest AM peak hour observed in April had an hourly flow of 1,240 vehicles, 479 (34%) of those entered at Gessner. Approximately 30 percent (352 vehicles) of the carpools were observed to exit the transitway at Post Oak. These volumes are depicted in Figure 3. Vehicle volumes during the AM peak hour (based on vehicle demands) are approaching levels experienced prior to the implementation of the 3 + restriction during the peak hour. Traffic counters were placed at three locations along the transitway to evaluate peak flow rates. Data collected in 5-minute intervals was multiplied by 12 to obtain equivalent hourly flow rates. The data presented in this section of this report was collected on Wednesday, May 23, During the AM peak period, three critical locations have been identified for a detailed examination of flow rates: West of Gessner, East of Gessner, and at Silber (i.e., just west of Post Oak Exit/Eastern Extension merge). Table 3 presents these hourly flow rates at each location for a typical AM peak period as observed in May Figure 4 provides a graphical presentation of this data; time periods of demand exceeding capacity are indicated at each count location for an assumed LOS C capacity of 1,500 vehicles/hour (~). The impact of the 3 + restriction in reducing the flow rates below capacity is apparent after 6:45 am. Those observed east of Gessner and at Silber peak later and for longer duration than that west of Gessner; this is a result of travel time and those choosing to enter the lane while "cheating" on the restricted period. t should also be noted that flow rates observed at Silber are lower and occur later during the AM peak period, a result of travel time and increasing vehicle headways. Travel Time and Speed Travel time and speed studies were completed on the freeway mainlanes and transitway in March The limits of the study were the Western and Eastern Terminus of the transitway. The results of this study for the AM peak period (by 30-minute headways) are presented in Table 4. Comparing a similar trip, speeds on the transitway 9

14 rj) C CO,.J g:; 0::: ::c: Q '"-l '"-l ~ lz ± ~ z 5 <!- 0 C 0::: rj)... rj) rj) ~ ' Q. - '"-l rj) 0:::!- ~ > ~ '"-l '"-l rj) u '"-l ::c: 0 ~~ u c: CQ ~ " z Q. ~A '"-l ::J CQ \$'~ ::c: 0::: ~ < CQ OLOKATY~ 5-Buses AD DCKS 8-Vaapools WEST 352-Cat-pools --; _ PARK ROW P&R BELT ~ P&R ~.~ fzj KATY FREEWAY WB +- _l_ -,.- - :.J~.~ cp / KATY FREEWAY EB 1-17-Buses 25-Buses '\ 17 -Vaopools. 8-Vanpools 727 -Carpools 446-Carpools 761-Vehicles 479-Vehicles 25-Vaopools 821-Carpools.! ~s 875-Vebicles u 37-Buses - :t- WAS HNGTON 42-Buses 17-\Taapools-! Vebicles ~ N r./) '"-l ~ ~ 'K>T TO SCALE. Figure 3. Katy Transitway Eastbound, AM Peak Hour Volumes, April 1990

15 Table 3. Katy Transitway Eastbound 5-Minute Flow Rates, May 1990 Observed Flow Rate in Vehicles per Hour* Time nterval West of Gessner East of Gessner At Silber 6:00-6:05 am :05-6: :10-6: :15-6: :20-6:25 6% :25-6: :30-6: :35-6: :40-6: % 6:45-6:50 15% :50-6: :55-7: :00-7:05 am :05-7: :10-7:15 3% :15-7: :20-7: :25-7: :30-7: % 648 7:35-7: :40-7: :45-7: :50-7: :55-8: :00-8:05 am :05-8: :10-8: :15-8: :20-8: :25-8: :30-8: :35-8: :40-8: :45-8: :50-8: :55-9: *Flow rate = (5-minute data) x 12 11

16 Figure Katy Transitway Flow Rates, Eastbound, AM Peak Period 1-10 KATY TRANSTWAY FLOWRATES EASTBOUND -- AM PEAK PEROD ' N l! :::> ' UJ w _j u H w > 1200 z H 900 w 1-- <(! 3: 0 600,E--R _j LL 300 -r /w-w ]:. t ~ \ ASSUMED CAPACTY=1500 vph 1 \ \,E.. -E \ \~ \ \ r / \ \,E-E -S / ~\ \ / \r \ w-~w -wy--.~ \-\/} \!,/\ l\ w. ""v ~ 'w-w--w-w ~ BOO 900 TME OF DAY -- AM PEAK PEROD NOTES: FLOWRATE= (5-Minute Data) * 12 W = West of Gessner; E = East of Gessner; S Data for Wednesday, May 23, 1990 At Silber

17 Table 4. Results of Travel Time Studies, AM Peak Period, March 1990 Enter Transitway at Gessner 1 Enter Transitway at Western Terminus 2 Start Time Transitwa~ Trin Freewa~ Trin Transitwa~ Trin Freewa~ Trin (minutes) (mph) (minutes) (mph) (minutes) (mph) (minutes) (mph) 6:00am :30am :00am :30am :00am :30am :00am :30am Average Trip Length = 5.65 miles 2 Trip Length = miles averaged 56 mph compared with 45 mph on the freeway mainlanes for the entire peak period. Maximum savings of almost 10-minutes per trip was realized for a trip along the transitway from the Western to Eastern Terminus. A plot of transitway and freeway running speeds along this route is presented by Figure 5. With the exceptions of the fringes of the peak period, transitway users receive travel time savings compared to a similar trip on the freeway mainlanes. Time differentials at the fringes are minimal and may be incurred at access points along the lane. Average running speeds on the transitway are greater than 50 mph throughout the peak period. Speed studies were also completed using automatic traffic counters at three locations. This equipment will estimate the speed of a vehicle and record it within a specified 5-mph range. Although speeds of individual vehicles are not recorded, the data (collected in Sminute intervals) can be used to identify specific operational characteristics of the transitway. The results of this analysis for the AM peak period are presented in Table 5. This data was collected in early April during weekday operations. Consider that the counting equipment may not have recorded the speed of every vehicle, however, the sample results provide insight as to transitway performance during inbound operations. The sample study of speeds east of the Gessner slip ramps indicate speeds averaging 40 mph during the AM peak period. This is a result of the merging operation of vehicle entering at Gessner and the reduced speed of the vehicles east of the slip ramps prior to accelerating 13

18 Figure Katy Freeway/Transitway Average Speeds, Eastbound, AM Peak Period -10 KATY FREEWAY/TRANSTWAY AVERAGE SPEEDS EASTBOUND -- AM PEAK PEROD '"""'.c:: 0. E D w n.. UJ (.!) z H z ::::> a: w (.!) <{ a: w ~ z > <{ ' ' ' ' 45 ' ' ' ' ' 40 )::._ r p P" / / / / / / / / / / / / / / / F-- 0 'T BOO TME OF DAY -- AM PEAK PEROD T Transi tway Speed: F Freeway Speed

19 Table 5. AM Peak Period Sample Speed Study Results East of Gessner Silber Eastern Extension Time #Vehicles Avg Speed #Vehicles AvgSpeed #Vehicles Avg Speed 6:00-6:15 am :15-6: :30-6: :45-7: :00-7:15 am :15-7: :30-7: :45-8: :00-8:15am % :15-8: :30-8: :45-9: NOTE: #Vehicles represents sample size for average speed determination; actual transitway flow rates may be higher. to free-flow speed. Speeds at Silber and on the Eastern Extension are generally in excess of 50 mph, indicating no major slowdowns as vehicles approach the merge. Capacity Analysis Level of service (LOS) on the transitway is estimated using the Highway Capacity Manual (5.). The analyses used volume data collected during the first months of operations upon completion of the Eastern Extension. The first analysis considers the transitway as a one-lane freeway and estimates the LOS at the maximum loading point east of the Gessner slip ramp. The LOS is based upon the observed transitway volume and criteria included in Table 3-1 of the HCM. Please note that the volumes vary on a daily basis; the maximum observed demands are presented. Previous studies (1) have assumed a transitway LOS C capacity of 1,500 vph. Table 6 presents the transitway LOS as calculated by both methods. Considering these values which represent the highest hour observed, the facility presently operates at a LOS B-C range using HCM procedures compared with LOS C-D using a capacity of 1,500 vph/lane. 15

20 Table 6. Basic Section Level-of-Service, AM Peak Hour Maximum Peak Start Date No. of Days Hour Demand HCM Method 1 'l.}s, LOS 0.50 B 0.40 B 0.61 c 0.41 B 0.54 B 0.50 B 0.60 c 0.54 B 0.60 c Assumed Capacity 2 'l.}s, LOS 0.66 c 0.53 B 0.81 D 0.55 c 0.73 c 0.67 c 0.79 D 0.72 c 0.80 D 1 Based upon maximum capacity assumed at 2,000 vph/lane. 2 Based upon maximum capacity assumed at 1,500 vph/lane. f the maximum 5-minute flow rates of Table 3 are used, the capacity analysis provides results of much greater concern. The peak 15-minutes during the AM peak hour resulted in an average flow rate of approximately 1,750 vph. Using HCM procedures, this results in a volume-to-capacity ratio of 0.88 and LOS D operations. Flow rates within the 1,500-1,850 vph range are observed prior to implementation of the 3 + restriction. Because of lower volumes during the restricted period, total traffic demands result in the peak hour LOS as reported. f the restriction were not to be implemented during the AM peak period, congestion could once again develop on the lane. f the transitway was assumed to be a freeway section with a one-lane ramp entering at Gessner, a capacity analysis of the AM peak hour ramp merge can also be completed. Considering the transitway demands of April 1990 as presented by Figure 3, a merge volume of 1,240 vph results in LOS C operations. Although this is 8 to 15 percent less than that observed in 1987 (1), the LOS of the merge has remained unchanged. Several studies have been completed by TTl on the operations at the Post Oak terminus of the Katy Transitway. Turning movement studies were completed in October 1989, January 1990, and March Using the results of the turning movement studies, the most efficient signal phasing (for each hour) at the intersection was determined using the TRANSYT-7F signal optimization model. To simplify this effort, simple 4-phase signal timing without overlaps was assumed for the analysis. The program was allowed to select 16

21 the appropriate cycle length resulting in the least amount of total intersection delay. These results for the 6:00-9:00 am peak period are presented in Table 7. Comparing the October 1989 and March 1990 results, intersection operations in terms of LOS are identical. However, the removal of approximately 800 vehicles during the AM peak period has reduced total intersection delay by 24 percent. Overall intersection operations have improved since the Eastern Extension of the transitway opened in January. Addition of a right-turn lane for North Post Oak northbound would provide additional delay reductions. Table 7. Summary of AM Peak Period Operations, Katy Transitway Post Oak Terminus AimroachLMonth Total Volume Total Delay Average Delay LOS (veh/hr) (veh-hrs) (secjveh) Transitway (EB) Approach October c January c March c All Approaches October c January c March c NOTE: Values reported represent entire 6:00-9:00am peak period. Summacy of AM Peak Period Operations Based upon the analyses presented in this report, the Katy Transitway is operating at an "acceptable" level of service during the AM peak period. n most cases, this equates to LOS C operations. There should, however, be some concern about operations in the transitway section east of Gessner. Since the Eastern Extension became operational, total transitway peak hour vehicle demand has increased by 14 percent to 1,240 vph. Demands west of Gessner have remained constant while the Gessner entrance increased from 330 vph to 479 vph (January- April); this represents a 45 percent increase. t can be concluded that many motorists previously did not use the lane (east of Gessner) because of the portion of the trip along Old Katy Road. These "new" users are attracted to the transitway because of the additional travel time savings using the Eastern Extension compared with the previous surface street route. 17

22 As indicated by Table 3 and Figure 4, flow rates exceeding 1,500 vph exist prior to implementation of the 3 + restriction at 6:45 am. This condition occurs only for a minute period as 2+ carpoolers "rush to get on the lane" before (and sometimes after) the restricted period. Since vehicle demand is significantly reduced during the restricted period, queueing does not occur on the transitway. Platoons of tightly spaced vehicles have been observed near egress points along the lane; however, vehicle headways usually increase as each begins to accelerate to 55 mph. The delays incurred in this manner are negligible compared to the overall travel time savings; these delays are synonymous with those incurred when entering a freeway. n summary, the transitway operates at an acceptable level of service with the existing occupancy requirements (3+ between 6:45-8:15am; 2+ other times). However, increases in transitway demand of 10 to 20 percent during the AM peak hour could significantly impact operations resulting in conditions comparable to those prior to implementation of the restriction. Modifications to the existing restrictive periods and/ or other innovative measures to manage demand may be necessary in the future if vehicle demands continue to increase. 18

23 OPTONS FOR MANAGNG DEMAND DURNG THE AM PEAK PEROD n a previous report (.1), TT examined alternatives to manage demand during the AM peak period. After reviewing the possible impacts of these options, METRO/SDHPT implemented a 3 + requirement between 6:45-8:15 am. The continuance of this requirement and other options will be examined in detail. The alternative demand management actions to be considered for the AM peak period include: 1. Voluntary spreading of peak-hour demand; 2. mposing a 3 + carpool definition during the peak hour; 3. Requiring authorization during the peak hour; and 4. Closing and/or metering entrance ramps during the peak hour. Voluntary Spreadina= of Peak Hour Demand Since the transitway does experience sharp peaking, if a relatively small percentage of the traffic using the transitway could be encouraged to alter its trip time in order to not be on the transitway during the peak hour, the congestion problem could be "solved." n an attempt to shift transitway demand, METRO, in September 1987, sent carpoolers a post card requesting users to adjust their travel. This voluntary effort was unsuccessful in reducing peak hour demand, and it appears that the motorists in Houston were unwilling or unable to adjust their work trip travel to accommodate such a request. A mandatory demand management technique was then implemented in October mposina= a 3 + Carpool Definition durin&: the Peak Hour The occupancy requirement to use the transitway can be adjusted to reduce vehicular volume during the peak hour. This alternative was implemented on the Katy Transitway in October The 3+ requirement, imposed between 6:45-8:15 am, has been successful in reducing congestion on the lane during the peak hour. The unique design (barrier separated transitways with a limited number of access/ egress locations) and regular, routine enforcement associated with the transitway greatly enhanced the feasibility of this demand management approach. Data available through December 1989 examining the 19

24 impacts of this alternative are presented for informational purposes in Table 8. Detailed evaluation of the impact of this demand management alternative is beyond the scope of this report, however, possible impacts should the 3 + requirement be removed are examined. Table 8. AM Travel Volumes Before and After Change in Occupancy Requirements, Katy Freeway Corridor "Representative" Value After Occupancy Change Pre-Occupanc~ 11/~8 and 12/88 03/89 12/89 Travel Volumes Change Value Value % Change 3 Value % Change 3 Value % Change 3 Daily Transitway Person Volume 18,880 16,595-12% 17,831-6% 18,352-3% AM Peak-Period Person Volume, Total 8,780 7,265-17% 7,945-10% 7,523-14% 2 Person Carpools 5,090 2,490-51% 2,800-45% 2,998-41% 3 + Person Carpools 935 1, % 1, % 1, % Total, Carpool Riders 6,025 4,325-28% 4,705-22% 4,567-24% Bus Patrons 2,450 2, % 2, % 2, % Vanpool Riders % % % 7:00-8:00 am, Total Person Volume 4,320 2,915-33% 3,445-19% 3,079-28% Carpools 2,885 1,315-54% 1,705-39% 1,557-46% 2 Person Carpools 2, % % % Bus Patrons 1,310 1, % 1, % 1, % Vanpoolers % % % AM Peak Period Vehicle Volume, Total 2,900 1,950-33% 2,120-27% 2,155-26% Carpools 2,780 1,820-34% 1,990-28% 1,971-29% 7:00-8:00 am, Total Vehicle Volume 1, % % % 2 + Carpool Vehicles 1, % % % 2 Person Carpools 1, % % % 3+ Carpools % % % Carpool Vehicle Volume (6:00-7:00 and 8:15-9:30) 1,230 1,170-5% 1, % 1, % Freeway Mainlane Volumes, 6:00-9:30am Vehicles 15,300 15, % 16, % 19, % Total Persons 16,455 17, % 18, % 20, % Average Vehicle Occupancy % % % 1 This is the value representative of the trend line that existed prior to changing the occupancy requirement. t does not reflect the values for any particular month. 2 These are representative of the average of the November and December 1988 data. 3 The percent change in comparison to the representative pre-occupancy change value. Source: Reference (~. 20

25 The most basic reason for not reinstating a 2 + requirement is that -- disregarding the fact that transitway demand is estimated to increase at 2 to 3 percent per year-- today's transitway demand with a 2+ requirement exceeds the transitway capacity. The same conditions that existed in the Fall of 1988 that led to the 3 + decision would reoccur. Prior to opening the Eastern Extension of the transitway, constraints on the AM capacity of the Katy Transitway included: 1) the merge at an AM slip ramp from the inside freeway lane to the transitway in the vicinity at Bunker Hill; 2) the horizontal and vertical curvature on the structure approaching the Post Oak terminus of the transitway; and 3) the Post Oak terminus of the transitway ending at a signalized intersection. The opening of the Eastern Extension addressed only two of these controlling factors by removing approximately 60 percent of the transitway vehicle demand out of the Post Oak terminus. During the time period when a 2 + requirement existed during both the AM and PM peak hours, AM volumes were consistently 10 to 15 percent greater than PM volumes. Since the Eastern Extension opened, PM peak-hour volumes frequently exceed 1,600 vph and are resulting in delay problems. t is reasonable to assume that AM demands would be at least this great and possibly 10 to 15 percent greater. t is generally accepted that 1,400 vph to 1,500 vph represents the "capacity" of a transitway. Because of the highvolume merge that occurs at Gessner, 1,200 vph to 1,400 vph probably represents the desirable capacity of the section from Gessner to Post Oak. Quite simply, a 2 + requirement will exceed the capacity of the transitway. A major intent of the transitway will cease to exist. The high peak-hour volumes that would result with a reinstatement of 2+ occupancy requirement would increase the number of breakdowns experienced on the transitway. This may have the effect of reducing the travel time reliability offered by the transitway; an attribute that is very important to the success of the transitways. Similarly, as volumes on the transitway increase, concern over the safety of operations increases. At 1,800 vph, the lane would operate at an average 2 second headway between vehicles. When the transitways first opened, an operational guideline of 3 second headways, or 1,200 vph, was recommended. 21

26 t is expected that, in the design year, the Houston transitways will move 7,000 to 10,000 persons per hour per lane. This design volume has been used in justifying the lanes and in planning how future freeway demands will be handled. This design volume simply will not be attained with a 2 + carpool requirement. With the 2 + requirement, the Katy Transitway, operating at vehicular capacity, moved about 4,500 persons in the peak hour. Thus, there has always been an implicit assumption that, at some date, a 3 + requirement would be applied on the transitways at least during the peak hour to attain the design year volumes. With a 3 + carpool requirement, the transitways are expected to move 4,200 persons per hour in buses (85 buses at 50 persons per bus) and 3,800 persons per hour in carpools (1,200 vehicles at 3.2 persons per vehicle). Experience on other HOV lanes also suggests that a 7,000 to 10,000 hourly person volume will not be attained unless at least a 3 + occupancy requirement is in effect. Public comments have been received by METRO requesting removal of the 3 + requirement during the peak hour. t is perceived that since the Eastern Extension opened in January 1990, all capacity problems on the lane have been solved. Although the traffic signal at the Post Oak terminus was a problem, the capacity of the transitway would have been exceeded even without the signal. To address the complaints currently being received as a result of the 3 + requirement, one option is to reduce the length of the restricted period. The initial intent of the restriction was to assure free-flow on the transitway between 7:00 and 8:00 am. During the 15-minute transition periods before and after this hour, higher than usual violation rates were expected and observed. At present, volumes prior to 6:45 am are relatively high, and moving the restricted time from 6:45 to 7:00 does not appear appropriate. This time period is also critical so that vehicles legally entering the transitway prior to 6:45 am are able to clear the transitway by 7:00 am. However, a review of recent volume data suggests that transitway demand begins to drop after 7:45 am. Thus, there would be no strong technical argument against ending the restricted period at 8:00 am instead of 8:15 am. This is particularly true if adequate enforcement is provided and/or if innovative enforcement techniques are found to be feasible and effective. Careful monitoring of demands and violation rates should be continued as the 3 + violators begin to "cheat" on the 8:00 am time period. 22

27 Require Authorization durin~: the Peak Hour The authorization concept would be reintroduced. Carpools using the transitway during the peak hour would have to display a permit (possibly a permit that hangs from the rear view mirror). With appropriate use of enforcement and the surveillance, communications, and control system, implementation of this alternative appears feasible. Previous Til research (Table 9) has estimated the imposing authorization on transitway demand would reduce the demand by 40 percent. This estimate may be somewhat high in that the authorization procedure used was more stringent than would be employed were this concept reintroduced. However, since the operating agencies have control over the number of authorization permits issued, they can, in effect, be assured that an acceptable demand reduction is achieved through this approach. Since the 40 percent estimate may be high with a less stringent authorization procedure, a range of 20 percent to 40 percent is assumed to be representative of the demand reduction implications of authorization. This approach appears viable and should be considered for possible implementation, since it could also be used during the PM peak period. However, there are problems with this technique: 1. Adequately informing the public of the strategy will be difficult. n addition to other means of notifying the public, adequate signing will need to be provided to inform motorists of the requirements for using the transitway; 2. METRO will need to develop procedures and to commit resources for authorizing large volumes of vehicles; 3. Strict enforcement will be required; and 4. Since all demand management strategies are intended to adversely impact some current users of the transitway and since some confusion will exist over peak-hour only authorization, adverse public reaction may be generated. 23

28 Table 9. Estimated Factors for Converting Unauthorized Carpool Demand to Authorized Carpool Demand Data Source Katy Transitway, Houston (Change from Authorized to Unauthorized in August 1986) 1 Authorized as a Percent of Unauthorized 44% 3+ Volume during Authorization (12/85-5/86) = 187 /day 3+ Volume without Authorization (9/86-2/87) = 428/day Katy Transitway Carpool Survey (10/86) Response to question, "f it were still necessary to be issued a permit by METRO to be authorized to use the transitway, would you be using the transitway?" Yes = 55%; No = 23%; Not Sure = 22% Response to question, "f METRO finds it necessary to issue permits to maintain free flow, would you be willing to get a permit?" 66% 76% Katy Transitway Carpool Survey (4/87) Response to question, "f you carpooled prior to August 1986 but did not use the transitway, why did you choose to not use the transitway (responses from 3+ carpools)?" 58% Authorized process was too cumbersome; 48% Other Range of Values Average Value Suggested Value for Houston Planning 62% 44% to 76% 62% 60% 1 At the time authorization was eliminated, the eligible carpool definition was also reduced from 3 + to 2 +. Source: Reference (Q). f this option is to be implemented, it is recommended that the authorization process be required for using the Katy Transitway during the entire AM peak period (6:00-9:00 am), thus capturing the majority of work trips. However, the authorization (or registration) process should be refined from that previously used. The previous method required carpoolers to take a driving test and have the vehicle routinely inspected. That portion of the authorization process should be discontinued. A possible authorization process could be based on some of the items listed below. 1. Potential users would be required to register as a "carpool group." Each carpool would be required to complete a form, with each person filling out 24

29 a portion of the same form. Standard questions could include name, home address, point of carpool formation, work destination, and time and point of transitway access. To assure validity of the application, it may be necessary to contact a random sample of applicants. 2. After receipt of all applications, METRO could issue permits to users of the transitway based upon their time and place of lane entrance and usual carpool occupancy. This provides for a demand management technique allowing for the highest vehicle occupancy. A priority pyramid could be established to assist in deciding which carpools would receive a permit. a. The total transitway demand should be kept at an acceptable level below capacity to assure free-flow conditions. To maintain 3 second headways, this demand should be less than 1,200 vehicles/hour east of the Gessner access. b. First priority must be given to buses and participants in the vanpooling program. All types of buses should be allowed on the lane including intercity and school buses. Since all buses and most vanpools adhere to some type of schedule, their time and point of transitway entrance is usually constant. c. After all buses and vanpools within a specified time period are allowed, carpools are authorized to use the lane with a priority to those with the highest occupancy. This would provide for some 2+ carpools on the lane; even during the peak hour. Since not all 2+ carpools who apply for registration would be allowed on the transitway because of capacity restraints, another selection process must be used. The first group logically to be rejected are 2+ carpools with an adult and a small child. A second group could include married couples that do not work at the same or close-by locations. These groups are not "real carpools" and most likely would never increase occupancy above 2-persons. This indicates that a long-term goal of modifying the definition of a carpool may be necessary to manage demand. 3. Since this process is based upon a time/occupancy/capacity restraint, enforcement could be a major problem. A routine sampling of users could be implemented. The sampling process could involve stopping random 25

30 vehicles, recording their authorization number and number of occupants. The time on the lane and occupancy level could later be checked against their application on file. This information could be used to warn users (with a letter or post card) if the occupancy requirement is not met. t is probably more difficult to comment on their time of use of the lane. Although the majority of users would enter the transitway within the time period stated on the application, this should not be included in any type of METRO response. This information, however, should be kept available as users reapply for the permit upon its expiration. t is probably not possible to impose a monetary fine on users that do not meet the occupancy and time of lane use information as indicated on their application. However, proper signing could be designed to allow ticketing of those violating a minimum 2 + requirement and/ or those without authorization during the restricted period. How this would be received in the court system must be investigated before this strategy would be implemented and should be a factor considered in the decision process. n many ways this possible authorization process is simpler than the previous method, although other difficulties have been introduced. A personal computer could be used to determine which users should be authorized to use the lane. "Border-line" cases could be evaluated by reviewing the application and personal contact by telephone. Although this authorization process is complicated, it does allow for a mix of buses, vanpools, and carpools (at the highest occupancy level) on the transitway while maintaining a nearcapacity vehicular volume. Close and/or Meter Entrance Ramps during the AM Peak Hour A final option involves reducing access to the transitway for all or part of the peak hour by either closing ramps or metering ramp volumes. Since the transitway essentially operates as a one-lane freeway, ramp control, which has successfully controlled freeway operations for several years, should be seriously considered. Geometries at each of the AM access points do cause specific problems. Generic problems that will be experienced at all locations are listed below. 26

31 1. Adequately informing the public of the strategy will be difficult. Again, adequate signing will need to be provided; 2. All access points must remain accessible to buses and vanpools. Enforcement of carpools using a ramp that does not allow carpool access will be difficult; 3. Extreme opposition can be expected from current users of any ramp to which control strategies are applied; and 4. f any strategy is implemented at either the western or intermediate access is affected, discrimination against longer or shorter trips does occur. Additional problems will occur at each ramp because of geometries, and each ramp should be evaluated on an individual basis. Operational plans for each strategy should be developed prior to implementation of any ramp metering or closure. Possible problems at each access point for the eastbound direction are discussed below. Metering of the Western Terminus slip ramp is not recommended because of high speed freeway operation and the lack of storage space for queued vehicles. Restricting access to buses and vanpools is possible, however, enforcement problems anse. An enforcement strategy could be developed in which the officer is stationed in the PM exit (facing eastbound) to discourage possible carpool users from entering the transitway. Any violators could then be followed by the enforcement vehicle and directed to exit at the Addicks Park-and-Ride lot. Restricting access only at the Western Terminus would not prevent carpools from entering at the park-and-ride or at Gessner. Access restrictions at the Addicks Park-and-Ride lot have a similar problem in that restricted vehicles could enter the lane at Gessner. Completion of the Addicks South Ramp would complicate matters by requiring demand management at two access points. f ramp meter signals were to be used at either the North or South Ramp, provisions are necessary to store queued vehicles. Considering the existing North Ramp, Park Row Street could be used to store the vehicles. However, should the street be extended eastward to intersect with Eldridge Parkway, storage on the street could not be safely implemented. Buses accessing the park-and-ride to pickup passengers could also be hindered while accessing the loading area. Total closure of the access to carpools is easily done because of geometries. 27

32 However, provisions are necessary for vanpools to be allowed access through the bus loading area to enter the transitway. A total closure of the Gessner slip ramp is not recommended because of the high volume of bus patrons entering the facility at that location. Restricting access to buses and vanpools is possible, but enforcement is a problem. A similar strategy as explored for Western Terminus access could be implemented using the westbound slip ramp exit. Because of lack of safe storage for any queued vehicles, the use of ramp meter signals is not practical. High speed operations along the freeway mainlanes could also cause problems for those unsure of access at the slip ramp. Although traffic congestion does exist in the freeway section adjacent to the slip ramp, vehicle speeds in the area are sporadic, ranging from stop-and-go to free-flow speeds. f any type of metering or ramp closure is implemented, the use of the changeable message signs must be expanded to aid in informing motorists. A detailed analysis of potential impacts on bus operations and vanpool programs should be completed prior to implementation. Public reaction from such action should also be considered. Recommendations Based on the current operations of the Katy Transitway during the AM peak period, the following options for controlling demand are recommended: 1. Retain the current 3+ carpool requirement from 6:45am to 8:15am. Based on current volumes being observed on the transitway, if, for other purposes such as public acceptance, it is felt that ending the restricted period at 8:00 am instead of 8:15 am is desirable, there would be no strong technical argument against such an action. However, it is recommended that the restricted period should begin no later than 6:45 am and end no earlier than 8:00am; 2. Consider implementing the authorization process based upon a time/ occupancy/ capacity restraint. This option for managing demand should be seriously considered if vehicle demand on the transitway continues to increase. 28